In the field of extruding complex shapes one of the more challenging items to produce is the flexible gaskets used for sealing refrigerators, automobile doors, hatches, and the like. These products utilize a complex cross section which requires considerable dexterity for the die to accurately reproduce the product. In order to accurately extrude these shapes, the die must completely fill while maintaining a continuous flow of plastic. The dies used in this type of process are generally referred to as profile dies. In manufacturing such dies it is often necessary to construct the die, use the die to see how it works and then, through a series of corrections, gradually bring the die into tolerance. This trial and error method is time consuming and expensive.
Profile dies are also used for extruding large plastic parts, for example fence posts and rails. In this instance, it is not a problem of intricate areas to fill, it is more a problem of providing a large volume of flow which is uniformly distributed over a large die outlet.
It is a purpose of this invention to construct a profile die which provides a balanced flow to the extremities of the die passage and to provide a more accurate and simpler way to construct a profile die within closer tolerances. A die with close tolerances will allow the product to be extruded with less material with a resulting savings in cost.
Another purpose of this invention is to distribute a large volume of molten plastic uniformly across a large die outlet while maintaining a reasonable flow rate so as to avoid dead spots which may result in scorching or buildup of plastic within the die.